Over the course of a grueling primary contest, it can only be expected that candidates will, on occasion, cross the line from fact to fiction. But this year’s cohort of presidential wannabes has made a particular point of choosing ideology over evidence, particularly on the topic of climate change. Ignoring the compelling evidence that discredits their skepticism, Republicans continue to deny human influences on global warming, depriving Americans of a much-needed honest debate on the topic.

In the most recent Republican debate, former Speaker of the House Newt Gingrich chastised President Obama for avoiding difficult truths. “I know among the politically correct,” he quipped, “you’re not supposed to use facts that are uncomfortable.” Perhaps he is right. Just a few short years after filming a commercial with former Democratic Speaker of the House Nancy Pelosi advocating for steps to combat climate change, Mr. Gingrich had a sudden change of heart. Describing the ad as “the dumbest thing I’ve done in recent years,” he now believes that “we don’t know” if man-made global warming is real.

The other Republicans remaining in the race are similarly unconvinced. Mitt Romney recently told a New Hampshire crowd: “We don’t know what’s causing climate change on this planet.” Texas Congressman Ron Paul, who is frighteningly close to becoming the most plausible anti-Romney candidate, called global warming “the greatest hoax I think that has been around for many, many years.” Not to be outdone, Texas Governor Rick Perry went so far as to criticize scientists for manipulating data in support of global warming in order to bankroll their projects.

The scientific community holds a different consensus. Data from reputable public authorities, including NASA and the National Oceanic and Atmospheric Administration (NOAA), suggest that surface temperatures on Earth have increased by up to 1.4 degrees Fahrenheit in the past century. One meta-analysis of nearly 1,400 climate researchers found that 97-98% supported the idea that human activity, particularly greenhouse gas emissions, are influencing climate change. That meets even the most rigorous statistical standards for confidence in a result.

Part of the Republican position is certainly a product of public opinion. Climate change skeptics, backed by shoddy information and the soapbox of the media, have fought tooth and nail to convince 20% of Americans that global warming is not occurring. Crucially, the same analysis suggests that 30% of Republicans and 53% of Tea Party supporters now hold that belief. Support for the notion that human activity is a driver of global warming is even lower.

In a nominating contest driven by the Republican base, particularly one in which Tea Party support is up for grabs, it’s good politics to preach to the choir. Even Jon Huntsman, the former presidential candidate who initially stood out from the field on this issue, backtracked in December with his claims that scientists “owe us more” to be convincing.

Republican denialism is built around ideology as much as on polling. Their positions reflect a broader anti-establishment philosophy that lumps scientists and other trained experts into the “elite” — a category defined, as best I can tell, as educated, intelligent, and wealthy individuals whose words and research cannot be taken at face value because they are too out of touch with mainstream America. Leading experts on important national issues may not be “Joe the Plumber.” But that’s exactly why I’m inclined to trust them.

Americans deserve an honest debate about competing policies and priorities, even on issues that may not be as immediately salient as the economy. Unfortunately, based on what we’ve seen so far, I wouldn’t hold your breath.